You can also choose "safe senders and recipients" as well as "blocked senders" from this page. However, it's probably more efficient to report the suspicious messages to us so that we can evaluate whether to block them campuswide. Click here to report.

When a user marks a message sender as blocked, the information is stored on the user object in the BlockedSendersHash Attribute. This Attribute is checked by Exchange Anti-Spam Filters.